1. Field of the Invention
The present invention is directed to an oil-in-water emulsion composition useful in the treatment of anorectal disorders such as hemorrhoids and use of the composition in the treatment of anorectal disorders such as hemorrhoids.
2. Description of Related Art
Hemorrhoids, a common ailment suffered by as many as nine out of ten Americans at some point in their lives, are swollen varicose veins in the mucous membrane inside or just outside the rectum. Hemorrhoids can be caused by constipation and the straining associated therewith as the excessive pressure involved can cause a fold of the membranous rectal lining to slip down, resulting in a pinching of the veins and subsequent irritation. Other causes may include diseases of the digestive tract resulting in an infection and diseases which obstruct blood flow, putting increased pressure on the hemorrhoidal veins. For example, pregnant women are prone to suffer hemorrhoids because of the pressure on the veins in the abdomen.
Hemorrhoidal symptoms can range from no noticeable symptoms to itching and mild discomfort to pain and/or bleeding. Once formed, the hemorrhoidal condition typically worsens over time, hence prompt treatment is desirable even in mild cases with few or no noticeable symptoms.
Treatment methods for hemorrhoids include soothing by immersion in a warm bath, application of ointments, gels and suppositories and surgery to curtail bleeding and to remove varicose veins. A single method of treatment or combination of treatment methods may be employed.
A number of patents and patent applications disclose and claim hemorrhoidal treatments. For example, U.S. patent application publication number 20040037888 discloses a gel preparation comprising a cellulose gelling agent, propylene glycol, and active ingredients. The water based system facilitates solublization of active ingredients but lacks the desirable tactile feeling of a cream and most likely the endurance at the site of treatment of a cream.
Related U.S. Pat. Nos. 5,234,957, 5,332,576 and 5,446,070 teach a composition comprising a polysaccharide bioadhesive carrier that is preferably water free. Active ingredients are dissolved in a solvent other than water. While this may facilitate preparation of the composition, the absence of water may impact the delivery of the active ingredient to body tissues. Evidence for this is found in U.S. Pat. No. 5,234,957 which teaches the use of concentrations of anesthetic actives substantially higher than approved FDA dosage amounts.
U.S. Pat. No. 6,582,724 discloses a composition which includes a hydroxide releasing agent such that the pH of the composition is pH 8.0 to pH 13. Such an alkaline pH would impact the stability of many active agents and preservation of the integrity of the composition over time would require special efforts.
U.S. patent application publication number 20020192273 discloses an adhesive patch for application of a therapeutic formulation for the treatment of hemorrhoids. Not only is a patch substrate required but also a pressure sensitive adhesive. Self application of such a patch to affected hemorrhoidal tissue may be fraught with some difficulty. Accomplishing adhesion at the desired location and/or discomfort in removing a patch adhered to hemorrhoidal tissue are exemplary of these difficulties.
U.S. patent application publication number 20030054017 claims a general method for application of a topical anesthetic to the skin. The method includes incorporating an anesthetic in a lipophilic base into a volatile solvent such as alcohol which will evaporate upon application to the skin. The disclosed composition is best suited for anesthetics which are preferentially soluble in non-polar/non-aqueous medium.
Many commercial preparations are available on the market for treatment of hemorrhoids. Many of these products are cream based preparations. Cream based compositions have the desirable properties of good tactile sensation and persistence on the area of treatment for a period of time. However, known cream based preparations typically suffer the significant deficiency of not dissolving many topical anesthetic agents and/or vasoconstrictors which are desirable active agents. While such agents may be physically dispersed in a cream, homogenous distribution as well as delivery to affected tissues may be problematic.
Hence, there remains a need for a cream type hemorrhoidal treatment with improved compatibility with dispersion and delivery of water soluble active agents.